.one {
    background-color:blue; 
    width: 40vw; 
    height: 500px;
    transition: width 1s;
}

.one:hover {
    width: 90vw;
    transition: 1s;
}

.two {
    background-color:green; 
    width: 20vw; 
    height: 500px;
}

.three {
    background-color:red; 
    width: 40vw; 
    height: 500px;
    transition: width 1s;
}

.three:hover {
    width: 90vw;
    transition: 1s;
}